Effects of Various Antibiotics on the Excitability of Newt Ectodermal Cells in vitro: (amphibian embryos/epidermal action potential/cell culture/antibiotics).

With the addition of actinomycin D (AMD), cycloheximide (CH) or tunicamycin (TM) to a culture medium at 23°c, the epidermal action potentials (EAPs) of the cultured epidermal explants or monolayered cell colonies taken from newt embryos were examined for confirmation of their relationship to transcriptional and translational events. EAPs of ectodermal cells from the pregastrula were first recorded after 84 hr of monolayered cell culture in FCS-Steinberg's medium. The addition of 10 μg/ml CH or 1 μg/ml TM for 36 hr prevented the appearance of these potentials in cells precultured in FCS-Steinberg's medium for 60 hr. Ectodermal cells precultured in FCS-Steinberg's medium for 68 hr generated the EAPs after they were cultured in the same concentration of CH or TM for 28 hr. Thus, it appears that certain proteins and glycoproteins may be responsible for evoking the EAPs and that these molecules are synthesized at about 68 hr in culture following the pregastrula stage. Ectodermal cells precultured in FCS-Steinberg's medium for 48 hr generated EAPs after they were cultured in 0.5 μg/ml AMD for 72 hr. Cells precultured for 36 hr failed to produce the EAPs even when they were cultured in the same concentration of AMD for 84 hr.